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Check: SRG-NET-000362-RTR-000113

Router SRG: SRG-NET-000362-RTR-000113 (in versions v5 r1 through v4 r1)

Title

The router must be configured to have Internet Control Message Protocol (ICMP) unreachable notifications disabled on all external interfaces. (Cat II impact)

Discussion

The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Routers automatically send ICMP messages under a wide variety of conditions. Host unreachable ICMP messages are commonly used by attackers for network mapping and diagnosis.

Check Content

Review the device configuration to determine if controls have been defined to ensure the router does not send ICMP unreachable notifications out to any external interfaces. If ICMP unreachable notifications are enabled on any external interfaces, this is a finding.

Fix Text

Disable ICMP unreachable notifications on all external interfaces.

Additional Identifiers

Rule ID: SV-207153r856637_rule

Vulnerability ID: V-207153

Group Title: SRG-NET-000362

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CCIs

CCIs tied to check.

Number	Definition
CCI-002385	Protect against or limit the effects of organization-defined types of denial-of-service events.

Controls

Controls tied to check. These are derived from the CCIs shown above.

Number	Title
SC-5	Denial of Service Protection